[backport#15931 4/9] Add block_height field in struct Confirmation

Summary:
At wallet loading, we rely on chain state querying to retrieve
height of txn, to do so we ensure that lock order is respected
between cs_main and cs_wallet.

If wallet loaded is the wallet-tool one, all wallet txn will
show up with a height of zero. It doesn't matter as confirmation
height is not used by wallet-tool.

Reorder arguments and document Confirmation calls to avoid
ambiguity.

Fixes nits left from #16624

https://github.com/bitcoin/bitcoin/pull/15931/commits/5971d3848e09abf571e5308185275296127efca4

Depends on D7508

Partial backport of Core PR15931

Test Plan:

ninja check check-functional

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D7509